1. Field of the Invention
The present invention relates to an optical recording medium, and more particularly, to an optical recording medium having a scratch-off material layer applied on the optical recording medium.
2. Description of the Prior Art
Increasingly popular in multimedia applications, digital optical discs have advantages of low cost, high compatibility and long data preservation time. Examples include a compact disc read-only memory (CD-ROM), a CD-recordable (CD-R), a CD-rewritable (CD-RW) and a digital video disc (DVD). Each of these has become major recording medium of data storage by virtue of their thin size and high storage capacity to record large amounts of information containing characters, voice, and images.
Please refer to FIG. 1 and FIG. 2. FIG. 1 is a top view of a conventional compact disc (CD) 10. FIG. 2 is a cross-sectional diagram of the CD 10 shown in FIG. 1 along a line I-I″. As shown in FIG. 1 and FIG. 2, the CD 10 includes a transparent substrate 12, a reflective layer 16 formed on the transparent substrate 12, a protective layer 18 formed on the reflective layer 16, and a printing layer 20 formed on the protective layer 18. The transparent substrate 12 also includes an opening 22 formed in central of the transparent substrate 12, and a spiral groove 24 formed on a surface of the transparent substrate 12. Typically, the CD 10 has a diameter of approximately 120 millimeter (mm) and the central opening 22 has a diameter of approximately 15 mm. The transparent substrate 12 is made of polycarbonate (PC) or polymethylmethacrylate (PMMA), and has a thickness of approximately 1.2 mm. The reflective layer 16 is made of aluminum (Al) metal, the protective layer 18 comprises acrylic resin, polycarbonate resin or ultraviolet (UV) curing resin, and has a thickness of between 1 to 100 micrometers (μm), and the printing layer 20 comprises oil printing ink or water printing ink.
The optical recording medium, such as the CD 10, always utilizes an optical read head (not shown in FIG. 1 and FIG. 2), which emits laser light to penetrate and irradiate the transparent substrate 12, to record digital data in pits 26 of the spiral groove 24 along the curvature of the transparent substrate 12 or read the digital data stored in the pits 26. Increasingly popular in personal computers (PCs) and audio-visual equipments, the information stored in the optical recording medium, such as computer software, music or images, brings a lot of convenience and fun to people. However, the general optical recording medium is easy to mass copy illegally with a CD burner or other machines, which effects the rights and interests of factories, stores, and users who bought an original edition CD. In addition, users of the illegally copied disc are not provided with service, technological support, product guarantees, or software upgrades. In order to prevent the above problems, and provide perfect service and guarantees to the users, it is important to prevent illegal copying and buying of optical discs and to increase sales of the original optical disc.